Patent documents U.S. Pat. No. 6,699,871 (issued in 2004) and WO 2003/004498 describe derivatives of beta-amino tetrahydrotriazolo-[4,3-α]pyrazine that are strong dipeptidyl peptidase-4 (DPP-4) inhibitors. The two above mentioned patent documents also particularly mention (2R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-α]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl) butan-2-amine (sitagliptin). The scope of the above mentioned patent documents generally comprises also salts. However, the above mentioned patent documents did not mention any particular salts.
Some pharmaceutically acceptable salts of sitagliptin and their preparation are described in the patent applications EP 1 654 263 (2004), EP 1 909 776 (2006) and WO2009/085990. The patent application WO 2005/072530 relates to other salts of sitagliptin, including the salt with tartaric acid and its crystalline form.